Lower blood sugar may be good for the brain, study shows

People with elevated blood sugar levels – even those not high enough for diabetes or pre-diabetes – are more likely to have memory problems than people with lower levels, a study of 141 people has shown.

The results suggest that people within the normal range could help prevent cognitive problems as they age by lowering their blood sugar levels, said the author of the study, Agnes Floel of Charite University Medicine in Berlin. The work was published online Wednesday in the journal Neurology.

Floel suggested reducing calories and increasing exercise should be tested to see if those could affect the levels and attendant problems.

The researchers looked at 141 people, with an average age of 63. They did not have diabetes or pre-diabetes, were not overweight, and did not drink or smoke much. They also did not have thinking or memory impairment.

Their memories and blood sugar levels were tested. They were asked, for example, to recall a list of 15 words a half hour after hearing them. Recalling fewer words was associated with higher blood sugar levels. People with higher blood sugar levels also had smaller volumes in the hippocampus.

Earlier research has shown “deleterious effects of diabetic glucose levels on brain structure, particularly the hippocampus,” the researchers wrote. Impaired glucose tolerance and Type 2 diabetes also have been associated with lower cognitive function and a higher incidence of dementia, including Alzheimer's disease, they wrote.

The hippocampus is a part of the brain important in memory and spatial navigation. It is one of the first regions of the brain to suffer damage in people who have Alzheimer's disease.

The current study not only confirms "previous associations between non-diabetic glucose levels and memory performance and hippocampal volume" but also serves "to substantially extend these findings by conducting more detailed neuroimaging protocols," the scientists wrote.